Highlighting bash code with knitr / rmarkdown

Question

I'm trying to generate an HTML report using RStudio, R Markdown and knitr. In the report I would like to display some bash code. I do not want to run the code but I would like it to be highlighted.

It has been mentioned in another question but the suggestion there doesn't work for me. Here's what I've tried so far:

---
title: "bash highlighting?"
output: html_document
---
```{r, engine = 'bash', eval = FALSE}
for foo in (ls bar)
do
  echo $foo
done
```

```{bash, eval = FALSE}
for foo in (ls bar)
do
  echo $foo
done
```

Neither of these give me highlighting in the HTML document. I know it's possible because I remember seeing it somewhere a week or so ago, but I can't find it anymore! Does anyone know how I can achieve it?

Thanks for reading,

Tom

Edit: I just found this answer, which suggests using the following code block in the .Rmd

<link rel="stylesheet" href="http://yandex.st/highlightjs/7.3/styles/default.min.css">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
<script src="http://yandex.st/highlightjs/7.3/highlight.min.js"></script>
<script>
$(document).ready(function() {
  $('pre code').each(function(i, e) {hljs.highlightBlock(e)});
});
</script>

This works for the bash code in the document but kills the highlighting for the R code!

## R version 3.2.0 (2015-04-16)
## Platform: x86_64-pc-linux-gnu (64-bit)
## Running under: Ubuntu 14.04.2 LTS
## 
## locale:
##  [1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C              
##  [3] LC_TIME=en_AU.UTF-8        LC_COLLATE=en_AU.UTF-8    
##  [5] LC_MONETARY=en_AU.UTF-8    LC_MESSAGES=en_AU.UTF-8   
##  [7] LC_PAPER=en_AU.UTF-8       LC_NAME=C                 
##  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
## [11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C       
## 
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets  methods   base     
## 
## loaded via a namespace (and not attached):
## [1] formatR_1.2     tools_3.2.0     htmltools_0.2.6 yaml_2.1.13    
## [5] rmarkdown_0.5.1 knitr_1.10      stringr_0.6.2   digest_0.6.8   
## [9] evaluate_0.7

Answer 1

The default syntax highlighting theme does not work well for non-R code chunks, and you can use other themes, e.g. pygments

---
title: "Bash Highlighting"
output:
  html_document:
    highlight: pygments
---

```{r, engine = 'bash', eval = FALSE}
for foo in (ls bar)
do
  echo $foo
done
```

Answer 2

OK, figured it out thanks to the comments. It seems it's RStudio which is not playing nice with the highlighting. When I keep the intermediate markdown file as in.md:

---
title: "Bash Highlighting"
output:
  html_document:
    keep_md: true
---

```{r, engine = 'bash', eval = FALSE}
for foo in (ls bar)
do
  echo $foo
done
```

then convert to html with pandoc using e.g. the CSS from BioConductor:

pandoc -s in.md \
    -c https://hedgehog.fhcrc.org/bioconductor/branches/RELEASE_3_1/madman/Rpacks/BiocStyle/inst/resources/html/bioconductor.css \
    -t html -o out.html

I get nice code highlighting for R and bash.

Thanks!